Childhood Medulloblastoma: Current Therapies, Emerging Molecular Landscape and Newer Therapeutic Insights

Mechanistic insights into medulloblastoma relapse

Pediatric brain tumors are the leading cause of cancer-related deaths in children, with medulloblastoma (MB) being the most common type. A better understanding of these malignancies has led to their classification into four major molecular subgroups. This classification not only facilitates the stratification of clinical trials, but also the development of more effective therapies. Despite recent progress, approximately 30% of children diagnosed with MB experience tumor relapse. Recurrent disease in MB is often metastatic and responds poorly to current therapies. As a result, only a small subset of patients with recurrent MB survive beyond one year. Due to its dismal prognosis, novel therapeutic strategies aimed at preventing or managing recurrent disease are urgently needed. In this review, we summarize recent advances in our understanding of the molecular mechanisms behind treatment failure in MB, as well as those characterizing recurrent cases. We also propose avenues for how these findings can be used to better inform personalized medicine approaches for the treatment of newly diagnosed and recurrent MB. Lastly, we discuss the treatments currently being evaluated for MB patients, with special emphasis on those targeting MB by subgroup at diagnosis and relapse.

FANCD2 deficiency sensitizes SHH medulloblastoma to radiotherapy via ferroptosis

Radiotherapy is one of the standard therapeutic regimens for medulloblastoma (MB). Tumor cells utilize DNA damage repair (DDR) mechanisms to survive and develop resistance during radiotherapy. It has been found that targeting DDR sensitizes tumor cells to radiotherapy in several types of cancer, but whether and how DDR pathways are involved in the MB radiotherapy response remain to be determined. Single-cell RNA sequencing was carried out on 38 MB tissues, followed by expression enrichment assays. Fanconi anemia group D2 gene (FANCD2) expression was evaluated in MB samples and public MB databases. The function of FANCD2 in MB cells was examined using cell counting assays (CCK-8), clone formation, lactate dehydrogenase activity, and in mouse orthotopic models. The FANCD2-related signaling pathway was investigated using assays of peroxidation, a malondialdehyde assay, a reduced glutathione assay, and using FerroOrange to assess intracellular iron ions (Fe2+ ). Here, we report that FANCD2 was highly expressed in the malignant sonic hedgehog (SHH) MB subtype (SHH-MB). FANCD2 played an oncogenic role and predicted worse prognosis in SHH-MB patients. Moreover, FANCD2 knockdown markedly suppressed viability, mobility, and growth of SHH-MB cells and sensitized SHH-MB cells to irradiation. Mechanistically, FANCD2 deficiency led to an accumulation of Fe2+ due to increased divalent metal transporter 1 expression and impaired glutathione peroxidase 4 activity, which further activated ferroptosis and reduced proliferation of SHH-MB cells. Using an orthotopic mouse model, we observed that radiotherapy combined with silencing FANCD2 significantly inhibited the growth of SHH-MB cell-derived tumors in vivo. Our study revealed FANCD2 as a potential therapeutic target in SHH-MB and silencing FANCD2 could sensitize SHH-MB cells to radiotherapy via inducing ferroptosis. © 2024 The Pathological Society of Great Britain and Ireland.

Evolution of neurosurgical advances and nuances in medulloblastoma therapy

Medulloblastoma, the most common malignant brain tumor in children, presents a complex treatment challenge due to its propensity for infiltrative growth within the posterior fossa and its potential attachment to critical anatomical structures. Central to the management of medulloblastoma is the surgical resection of the tumor, which is a key determinant of patient prognosis. However, the extent of surgical resection (EOR), ranging from gross total resection (GTR) to subtotal resection (STR) or even biopsy, has been the subject of extensive debate and investigation within the medical community. Today, the impact of neurosurgical EOR on the prognosis of medulloblastoma patients remains a complex and evolving area of investigation. The conflicting findings in the literature, the challenges posed by critical surrounding anatomical structures, the potential for surgical complications and neurologic morbidity, and the nuanced interactions with molecular subgroups all contribute to the complexity of this issue. As the field continues to advance, the imperative to strike a delicate balance between maximizing resection and preserving quality of life remains central to the management of medulloblastoma patients.

Identification and validation of a metabolism-related gene signature for predicting the prognosis of paediatric medulloblastoma

Medulloblastoma (MB) is a malignant brain tumour that is highly common in children and has a tendency to spread to the brain and spinal cord. MB is thought to be a metabolically driven brain tumour. Understanding tumour cell metabolic patterns and characteristics can provide a promising foundation for understanding MB pathogenesis and developing treatments. Here, by analysing RNA-seq data of MB samples from the Gene Expression Omnibus (GEO) database, 12 differentially expressed metabolic-related genes (DE-MRGs) were chosen for the construction of a predictive risk score model for MB. This model demonstrated outstanding accuracy in predicting the outcomes of MB patients and served as a standalone predictor. An evaluation of functional enrichment revealed that the risk score showed enrichment in pathways related to cancer promotion and the immune response. In addition, a high risk score was an independent poor prognostic factor for MB in patients with different ages, sexes, metastasis stages and subgroups (SHH and Group 4). Consistently, the metabolic enzyme ornithine decarboxylase (ODC1) was upregulated in MB patients with poor survival time. Inhibition of ODC1 in primary and metastatic MB cell lines decreased cell proliferation, migration and invasion but increased immune infiltration. This study could aid in identifying metabolic targets for MB as well as optimizing risk stratification systems and individual treatment plans for MB patients via the use of a metabolism-related gene prognostic risk score signature.

13-Cis Retinoic Acid Induces Neuronal Differentiation in Daoy (Medulloblastoma) Cells Through Epigenetic Regulation of Topoisomerase IIβ

Medulloblastoma (MB) is a malignant tumor of the cerebellum that occurs in children and infants. Abnormal neuronal differentiation can lead to brain tumors, and topoisomerase IIβ (Top IIβ) plays an important role in neuronal differentiation. The aim of this study was to investigate the molecular mechanism of 13-cis retinoic acid (13-cis RA) promoting the expression of Top IIβ and inducing neuronal differentiation in human MB Daoy cells. The results showed that 13-cis RA inhibited the cell proliferation and induced cell cycle arrest in G0/G1 phase. The cells differentiated into a neuronal phenotype, with high expression of the neuronal marker microtubule-associated protein 2 (MAP2) and abundant Top IIβ, and obvious neurite growth. Chromatin immunoprecipitation (ChIP) assay showed that histone H3 lysine 27 tri-methylation (H3K27me3) modification in Top IIβ promoter decreased after 13-cis RA-induced cell differentiation, while jumonji domain-containing protein 3 (JMJD3) binding in Top IIβ promoter increased. These results suggest that H3K27me3 and JMJD3 can regulate the expression of Top IIβ gene, which is related to inducing neural differentiation. Our results provide new insights into understanding the regulatory mechanisms of Top IIβ during neuronal differentiation and imply the potential application of 13-cis RA in the clinical treatment of MB.

Exploring the Molecular Complexity of Medulloblastoma: Implications for Diagnosis and Treatment

Medulloblastoma is the most common malignant brain tumor in children. Over the last few decades, significant progress has been made in revealing the key molecular underpinnings of this disease, leading to the identification of distinct molecular subgroups with different clinical outcomes. In this review, we provide an update on the molecular landscape of medulloblastoma and treatment strategies. We discuss the four main molecular subgroups (WNT-activated, SHH-activated, and non-WNT/non-SHH groups 3 and 4), highlighting the key genetic alterations and signaling pathways associated with each entity. Furthermore, we explore the emerging role of epigenetic regulation in medulloblastoma and the mechanism of resistance to therapy. We also delve into the latest developments in targeted therapies and immunotherapies. Continuing collaborative efforts are needed to further unravel the complex molecular mechanisms and profile optimal treatment for this devastating disease.

Modern treatment strategies in pediatric oncology and hematology

Every year, approximately 400 00 children worldwide are diagnosed with cancer. Although treatment results in most types of childhood neoplasms are excellent with survival more than 80%, there are some with poor prognosis. Also recurrent and resistant to treatment childhood cancer remain a therapeutic challenge. Besides chemotherapy, which has been the basis of cancer therapy for years, molecular methods and precisely targeted therapies have recently found their usage. As a result of that, survival has improved and has positively impacted the rate of toxicities associated with chemotherapy (Butler et al. in CA Cancer J Clin 71:315-332, 2021). These achievements have contributed to better quality of patients' lives. Current methods of treatment and ongoing trials give hope for patients with relapses and resistance to conventional chemotherapy. This review focuses on the most recent progress in pediatric oncology treatments and discusses specific therapy methods for particular cancers types of cancer. Targeted therapies and molecular approaches have become more beneficial but research need to be continued in this field. Despite significant breakthroughs in pediatric oncology in the last few years, there is still a need to find new and more specific methods of treatment to increase the survival of children with cancer.

Metabolism-based targeting of MYC via MPC-SOD2 axis-mediated oxidation promotes cellular differentiation in group 3 medulloblastoma

Group 3 medulloblastoma (G3 MB) carries the worst prognosis of all MB subgroups. MYC oncoprotein is elevated in G3 MB tumors; however, the mechanisms that support MYC abundance remain unclear. Using metabolic and mechanistic profiling, we pinpoint a role for mitochondrial metabolism in regulating MYC. Complex-I inhibition decreases MYC abundance in G3 MB, attenuates the expression of MYC-downstream targets, induces differentiation, and prolongs male animal survival. Mechanistically, complex-I inhibition increases inactivating acetylation of antioxidant enzyme SOD2 at K68 and K122, triggering the accumulation of mitochondrial reactive oxygen species that promotes MYC oxidation and degradation in a mitochondrial pyruvate carrier (MPC)-dependent manner. MPC inhibition blocks the acetylation of SOD2 and oxidation of MYC, restoring MYC abundance and self-renewal capacity in G3 MB cells following complex-I inhibition. Identification of this MPC-SOD2 signaling axis reveals a role for metabolism in regulating MYC protein abundance that has clinical implications for treating G3 MB.

ZEB1 is a Subgroup-Specific Marker of Prognosis and Potential Drug Target in Medulloblastoma

Medulloblastoma (MB) is a malignant brain tumor that afflicts mostly children and adolescents and presents four distinct molecular subgroups, known as WNT, SHH, Group 3, and Group 4. ZEB1 is a transcription factor that promotes the expression of mesenchymal markers while restraining expression of epithelial and polarity genes. Because of ZEB1 involvement in cerebellum development, here we investigated the role of ZEB1 in MB. We found increased expression of ZEB1 in MB tumor samples compared to normal cerebellar tissue. Expression was higher in the SHH subgroup when compared to all other MB molecular subgroups. High ZEB1 expression was associated with poor prognosis in Group 3 and Group 4, whereas in patients with WNT tumors poorer prognosis were related to lower ZEB1 expression. There was a moderate correlation between ZEB1 and MYC expression in Group 3 and Group 4 MB. Treatment with the immunomodulator and histone deacetylase (HDAC) inhibitor fingolimod (FTY720) reduced ZEB1 expression specifically in D283 cells, which are representative of Group 3 and Group 4 MB. These findings reveal novel subgroup-specific associations of ZEB1 expression with survival in patients with MB and suggest that ZEB1 expression can be reduced by pharmacological agents that target HDAC activity.

Superenhancers as master gene regulators and novel therapeutic targets in brain tumors

Transcriptional deregulation, a cancer cell hallmark, is driven by epigenetic abnormalities in the majority of brain tumors, including adult glioblastoma and pediatric brain tumors. Epigenetic abnormalities can activate epigenetic regulatory elements to regulate the expression of oncogenes. Superenhancers (SEs), identified as novel epigenetic regulatory elements, are clusters of enhancers with cell-type specificity that can drive the aberrant transcription of oncogenes and promote tumor initiation and progression. As gene regulators, SEs are involved in tumorigenesis in a variety of tumors, including brain tumors. SEs are susceptible to inhibition by their key components, such as bromodomain protein 4 and cyclin-dependent kinase 7, providing new opportunities for antitumor therapy. In this review, we summarized the characteristics and identification, unique organizational structures, and activation mechanisms of SEs in tumors, as well as the clinical applications related to SEs in tumor therapy and prognostication. Based on a review of the literature, we discussed the relationship between SEs and different brain tumors and potential therapeutic targets, focusing on glioblastoma.

Research progress in molecular pathology markers in medulloblastoma

Medulloblastoma (MB) is the commonest primary malignant brain cancer. The current treatment of MB is usually surgical resection combined with radiotherapy or chemotherapy. Although great progress has been made in the clinical management of MB, tumor metastasis and recurrence are still the main cause of death. Therefore, definitive and timely diagnosis is of great importance for improving therapeutic effects on MB. In 2016, the World Health Organization (WHO) divided MB into four subtypes: wingless-type mouse mammary tumor virus integration site (WNT), sonic hedgehog (SHH), non-WNT/non-SHH group 3, and group 4. Each subtype of MB has a unique profile in copy number variation, DNA alteration, gene transcription, or post-transcriptional/translational modification, all of which are associated with different biological manifestations, clinical features, and prognosis. This article reviewed the research progress of different molecular pathology markers in MB and summarized some targeted drugs against these molecular markers, hoping to stimulate the clinical application of these molecular markers in the classification, diagnosis, and treatment of MB.

Radio-pathomic approaches in pediatric neuro-oncology: Opportunities and challenges

With medical software platforms moving to cloud environments with scalable storage and computing, the translation of predictive artificial intelligence (AI) models to aid in clinical decision-making and facilitate personalized medicine for cancer patients is becoming a reality. Medical imaging, namely radiologic and histologic images, has immense analytical potential in neuro-oncology, and models utilizing integrated radiomic and pathomic data may yield a synergistic effect and provide a new modality for precision medicine. At the same time, the ability to harness multi-modal data is met with challenges in aggregating data across medical departments and institutions, as well as significant complexity in modeling the phenotypic and genotypic heterogeneity of pediatric brain tumors. In this paper, we review recent pathomic and integrated pathomic, radiomic, and genomic studies with clinical applications. We discuss current challenges limiting translational research on pediatric brain tumors and outline technical and analytical solutions. Overall, we propose that to empower the potential residing in radio-pathomics, systemic changes in cross-discipline data management and end-to-end software platforms to handle multi-modal data sets are needed, in addition to embracing modern AI-powered approaches. These changes can improve the performance of predictive models, and ultimately the ability to advance brain cancer treatments and patient outcomes through the development of such models.

Intracranial Tumors in the First Year of Life

Intracranial tumors in the first year of life are rare and, in this age group, are the second most common type of pediatric cancer after leukemias. As the more common solid tumor in neonates and infants, they present some peculiarities such as the high incidence of malignancies. Routine ultrasonography made easier to detect intrauterine tumors, but diagnosis can be delayed due to the lack or scarcity of recognizable symptoms. These neoplasms are often very large and highly vascular. Their removal is challenging, and there is a higher rate of morbidity and mortality than seen in older children, adolescents, and adults. They also differ from older children with respect to location, histological features, clinical behavior, and management. Pediatric low-grade gliomas represent 30% of the tumors in this age group and comprise circumscribed and diffuse tumors. They are followed by medulloblastoma and ependymoma. Other non-medulloblastoma embryonal neoplasms, former known as PNETS, are also commonly diagnosed in neonates and infants. Teratomas have an expressive incidence in newborns but decline gradually until the end of the first year of life. Immunohistochemical, molecular, and genomic advances are impacting the understanding and targeting of the treatment of some tumors, but, despite all these advances, the extent of resection remains the most important factor in the prognosis and survival of almost all types of tumors. The outcome is difficult to estimate, and 5-year survival ranges from one-quarter to three-quarters of the patients.

A Phase I Trial of TB-403 in Relapsed Medulloblastoma, Neuroblastoma, Ewing Sarcoma, and Alveolar Rhabdomyosarcoma

PURPOSE

Placental growth factor (PlGF) and its receptor neuropilin 1 are elevated in malignant embryonal tumors and mediate tumor progression by promoting cell proliferation, survival, and metastasis. TB-403 is a blocking monoclonal antibody against PlGF that inhibits tumor growth and increases survival in orthotopic medulloblastoma models.

PATIENTS AND METHODS

We conducted a phase I, open-label, multicenter, dose-escalation study of TB-403 in pediatric subjects with relapsed or refractory cancers. The study involved four dose levels (20 mg/kg, 50 mg/kg, 100 mg/kg, 175 mg/kg) using a 3 + 3 dose-escalation scheme. Subjects received two doses of TB-403 (days 1 and 15) per cycle. After cycle 1, temozolomide or etoposide could be added. The primary objective was to determine the maximum tolerated dose (MTD) of TB-403 monotherapy during a dose-limiting toxicity assessment period. The secondary and exploratory objectives included efficacy, drug pharmacokinetics, and detection of pharmacodynamic biomarkers.

RESULTS

Fifteen subjects were treated in four dose levels. All subjects received two doses of TB-403 in cycle 1. Five serious treatment-emergent adverse events were reported in 3 subjects, but MTD was not reached. While no complete nor partial responses were observed, 7 of 11 relapsed subjects with medulloblastoma experienced stable disease, which persisted for more than 100 days in 4 of 7 subjects.

CONCLUSIONS

TB-403 was safe and well tolerated at all dose levels. No MTD was reached. The results look encouraging and therefore warrant further evaluation of efficacy in pediatric subjects with medulloblastoma.

O-GlcNAcylation promotes cerebellum development and medulloblastoma oncogenesis via SHH signaling

Cerebellar development relies on a precise coordination of metabolic signaling, epigenetic signaling, and transcriptional regulation. Here, we reveal that O-GlcNAc transferase (OGT) regulates cerebellar neurogenesis and medulloblastoma growth via a Sonic hedgehog (Shh)-Smo-Gli2 pathway. We identified Gli2 as a substrate of OGT, and unveiled cross-talk between O-GlcNAc and epigenetic signaling as a means to regulate Gli2 transcriptional activity. Moreover, genetic ablation or chemical inhibition of OGT significantly suppresses tumor progression and increases survival in a mouse model of Shh subgroup medulloblastoma. Taken together, the data in our study provide a line of inquiry to decipher the signaling mechanisms underlying cerebellar development, and highlights a potential target to investigate related pathologies, such as medulloblastoma.

Sonic hedgehog (Shh) signaling plays a critical role in regulating cerebellum development by maintaining the physiological proliferation of granule neuron precursors (GNPs), and its dysregulation leads to the oncogenesis of medulloblastoma. O-GlcNAcylation (O-GlcNAc) of proteins is an emerging regulator of brain function that maintains normal development and neuronal circuitry. Here, we demonstrate that O-GlcNAc transferase (OGT) in GNPs mediate the cerebellum development, and the progression of the Shh subgroup of medulloblastoma. Specifically, OGT regulates the neurogenesis of GNPs by activating the Shh signaling pathway via O-GlcNAcylation at S355 of GLI family zinc finger 2 (Gli2), which in turn promotes its deacetylation and transcriptional activity via dissociation from p300, a histone acetyltransferases. Inhibition of OGT via genetic ablation or chemical inhibition improves survival in a medulloblastoma mouse model. These data uncover a critical role for O-GlcNAc signaling in cerebellar development, and pinpoint a potential therapeutic target for Shh-associated medulloblastoma.

Targeting AKT and CK2 represents a novel therapeutic strategy for SMO constitutive activation-driven medulloblastoma

AIMS

Sonic hedgehog subtype medulloblastoma is featured with overactivation of hedgehog pathway and can be targeted by SMO-specific inhibitors. However, the resistance is frequently developed leading to treatment failure of SMO inhibitors. W535L mutation of SMO (SMOW535L ) is thought to be an oncogenic driver for Sonic hedgehog subtype MB and confer resistance to SMO inhibitors. The regulation network of SMOW535L remains to be explored in comparison with wild-type SMO (SMOWT ).

METHODS

In this study, we profiled transcriptomes, methylomes, and interactomes of MB cells expression SMOWT or SMOW535L in the treatment of DMSO or SMO inhibitor, respectively.

RESULTS

Analysis of transcriptomic data indicated that SMO inhibitor disrupted processes of endocytosis and cilium organization in MB cells with SMOWT , which are necessary for SMO activation. In MB cells with SMOW535L , however, SMO inhibitor did not affect the two processes-related genes, implying resistance of SMOW535L toward SMO inhibitor. Moreover, we noticed that SMO inhibitor significantly inhibited metabolism-related pathways. Our metabolic analysis indicated that nicotinate and nicotinamide metabolism, glycerolipid metabolism, beta-alanine metabolism, and synthesis and degradation of ketone bodies might be involved in SMOW535L function maintenance. Interactomic analysis revealed casein kinase II (CK2) as an important SMO-associated protein. Finally, we linked CK2 and AKT together and found combination of inhibitors targeting CK2 and AKT showed synergetic effects to inhibit the growth of MB cells with SMO constitutive activation mutation.

CONCLUSIONS

Taken together, our work described SMO-related transcriptomes, metabolomes, and interactomes under different SMO status and treatment conditions, identifying CK2 and AKT as therapeutic targets for SHH-subtype MB cells with SMO inhibitor resistance.

STAT3 in medulloblastoma: a key transcriptional regulator and potential therapeutic target

Medulloblastoma is the most common malignant brain tumor of childhood accounting for about 60% of all pediatric embryonal tumors. Despite improvements in the overall survival rate, this tumor still lacks an efficient, reliable, and less toxic therapeutic approach. Characterization of the molecular mechanisms involved in medulloblastoma initiation and progression is a crucial step for the development of effective therapies. Signal transducer and activator of transcription 3 is a convergence point for several signaling cascades that are implicated in medulloblastoma tumorigenesis. Accumulated evidence has revealed the pivotal role of signal transducer and activator of transcription 3 in medulloblastoma pathogenesis such as proliferation, survival, angiogenesis, and immunosuppression as well as maintenance, drug resistance, and recurrence. In this review, we focus on the role of signal transducer and activator of transcription 3 in medulloblastoma tumorigenesis and discuss the recent advances of signal transducer and activator of transcription 3 inhibition as a promising developed strategy for medulloblastoma therapy.

Cross-translational models of late-onset cognitive sequelae and their treatment in pediatric brain tumor survivors

Pediatric brain tumor treatments have a high success rate, but survivors are at risk of cognitive sequelae that impact long-term quality of life. We summarize recent clinical and animal model research addressing pathogenesis or evaluating candidate interventions for treatment-induced cognitive sequelae. Assayed interventions encompass a broad range of approaches, including modifications to radiotherapy, modulation of immune response, prevention of treatment-induced cell loss or promotion of cell renewal, manipulation of neuronal signaling, and lifestyle/environmental adjustments. We further emphasize the potential of neuroimaging as a key component of cross-translation to contextualize laboratory research within broader clinical findings. This cross-translational approach has the potential to accelerate discovery to improve pediatric cancer survivors' long-term quality of life.

New Developments in the Pathogenesis, Therapeutic Targeting, and Treatment of Pediatric Medulloblastoma

Pediatric medulloblastoma (MB) is the most common pediatric brain tumor with varying prognoses depending on the distinct molecular subtype. The four consensus subgroups are WNT, Sonic hedgehog (SHH), Group 3, and Group 4, which underpin the current 2021 WHO classification of MB. While the field of knowledge for treating this disease has significantly advanced over the past decade, a deeper understanding is still required to improve the clinical outcomes for pediatric patients, who are often vulnerable in ways that adult patients are not. Here, we discuss how recent insights into the pathogenesis of pediatric medulloblastoma have directed current and future research. This review highlights new developments in understanding the four molecular subtypes’ pathophysiology, epigenetics, and therapeutic targeting. In addition, we provide a focused discussion of recent developments in imaging, and in the surgery, chemotherapy, and radiotherapy of pediatric medulloblastoma. The article includes a brief explanation of healthcare costs associated with medulloblastoma treatment.

BRCA2 deficiency increases sensitivity of medulloblastoma to Olaparib by inhibiting RAD51-mediated DNA damage repair system

PURPOSE

BRCA2 defect exists in glioma and regulates drug resistance of glioma to chemotherapy. However, its role in medulloblastoma and the mechanism is not known. To investigate the effects of BRCA2 deficiency combined with Olaparib in medulloblastoma and the mechanism.

METHODS

BRCA2 was knocked down by RNAi technology and cell proliferation was detected by CCK-8 assay. Cell apoptosis was determined by FACS analysis when the in vivo role of BRCA2 was explored with xenograft mice model. Western blotting technology was used to explore the mechanism of BRCA2.

RESULTS

Knockdown of BRCA2 enhanced the inhibitory effect of Olaparib on proliferation of Daoy and LN229 cells. The inhibition rate of Olaparib on Daoy or LN229 cells was 61.1%, 66.03% in shBRCA2 group, while it was 42.9%, 41.1% in shNC group. Overexpression of RAD51 partially reversed the effect of shBRCA2. In Daoy cells, apoptotic rate was 26.9% in Olaparib group and 58.9% in Olaparib/shBRCA2 group. However, it was 33.4% after RAD51 was overexpressed. It was the same in LN229 cells. In xenograft mice model, tumor volume in Olaparib and Olaparib/shBRCA2 group was 376.12 and 84.95mm³ when tumor weight was 0.46 g and 0.12 g. In addition, the level of RAD51, RAD50, MRE11, and NBS was increased by Olaparib alone but decreased reversely after knockdown of BRCA2 in Daoy cells.

CONCLUSIONS

Knockdown of BRCA2 increases the sensitivity of medulloblastoma cells to Olaparib and strengthens the efficacy of Olaparib in vitro and in vivo. Knockdown of BRCA2 causes DNA damage repair by regulating RAD51-mediated signaling pathway in Daoy cells.

Risk Factors for Survival in Patients With Medulloblastoma: A Systematic Review and Meta-Analysis

Background

Conventional parameters show limited and unreliable correlations with medulloblastoma prognosis.

Aim

To evaluate the factors influencing overall survival (OS), event-free survival (EFS), and progression-free survival (PFS) in patients with medulloblastoma.

Methods

PubMed, EMBASE, the Cochrane Library, and Web of Science were searched for studies published up to May 2021. The associations between various clinical and treatment factors and survival parameters were assessed.

Results

Twenty-nine studies (8455 patients) were included. Desmoplastic medulloblastoma (HR=0.41, 95%CI: 0.31-0.56), M0 disease (HR=2.07, 95%CI: 1.48-2.89), WNT, SSH, group 4 (all P<0.05 vs. group 3), GTR vs. STR (HR=1.37, 95%CI: 1.04-1.08), radiotherapy (HR=0.45, 95%CI: 0.20-0.80), craniospinal irradiation (HR=0.49, 95%CI: 0.38-0.64), and high 5hmC levels (HR=2.90, 95%CI: 1.85-4.55) were associated with a better OS. WNT, SSH, group 4 (all P<0.05 vs. group 3), residual tumor ≤1.5 cm2 (HR=2.08, 95%CI: 1.18-3.68), GTR vs. STR (HR=1.31, 95%CI: 1.03-1.68), craniospinal irradiation (HR=0.46, 95%CI: 0.37-0.57), high 5hmC levels (HR=3.10, 95%CI: 2.01-4.76), and <49 days between resection and radiotherapy (HR=2.54, 95%CI: 1.48-4.37) were associated with better PFS. Classic vs. desmoplastic medulloblastoma (HR=1.81, 95%CI: 1.04-3.16), SSH, WNT (both P<0.05 vs, non-SSH/non-WNT), GTR vs. STR (HR=2.01, 95%CI: 1.42-2.85), and radiotherapy (HR=0.31, 95%CI: 0.15-0.64) were associated with a better EFS.

Conclusion

Histology, molecular subgroup, GTR, and radiotherapy are significantly associated with survival parameters in patients with medulloblastoma. Nevertheless, high-quality prospective cohort studies are necessary to improve the conclusions.

Role of MicroRNAs in the Development and Progression of the Four Medulloblastoma Subgroups

Medulloblastoma is the most frequent malignant brain tumour in children. Medulloblastoma originate during the embryonic stage. They are located in the cerebellum, which is the area of the central nervous system (CNS) responsible for controlling equilibrium and coordination of movements. In 2012, medulloblastoma were divided into four subgroups based on a genome-wide analysis of RNA expression. These subgroups are named Wingless, Sonic Hedgehog, Group 3 and Group 4. Each subgroup has a different cell of origin, prognosis, and response to therapies. Wingless and Sonic Hedgehog medulloblastoma are so named based on the main mutation originating these tumours. Group 3 and Group 4 have generic names because we do not know the key mutation driving these tumours. Gene expression at the post-transcriptional level is regulated by a group of small single-stranded non-coding RNAs. These microRNA (miRNAs or miRs) play a central role in several cellular functions such as cell differentiation and, therefore, any malfunction in this regulatory system leads to a variety of disorders such as cancer. The role of miRNAs in medulloblastoma is still a topic of intense clinical research; previous studies have mostly concentrated on the clinical entity of the single disease rather than in the four molecular subgroups. In this review, we summarize the latest discoveries on miRNAs in the four medulloblastoma subgroups.

Clinical and molecular analysis of smoothened inhibitors in Sonic Hedgehog medulloblastoma

Background

Smoothened inhibitors (SMOi) have shown activity in Sonic Hedgehog (SHH) medulloblastoma, however this therapeutic class was not developed in children due to severe effects reported on growth. We hereby report long-term follow-up of young patients treated with SMOi for recurrent medulloblastoma.

Methods

Clinical data on response and toxicity from patients treated with vismodegib or sonidegib from 2011 to 2019 for a SHH medulloblastoma were retrospectively reviewed. Methylation analysis and whole exome sequencing were performed whenever possible.

Results

All patients with a somatic PTCH1 mutation responded to SMOi (6/8), including 2 prolonged complete responses. One patient was free of disease 8.2 years after treatment. SMOi was challenged again for 3 patients. Two of them had a response, one with SMOi alone, the other one in combination with temozolomide despite previous progression under monotherapy. SMO resistance mutations were found in patients from biopsy at relapse. Combination with temozolomide or surgery plus radiotherapy was associated with very long disease control in 2 patients. The most severe adverse events were myalgia and growth plate fusion with metaphyseal sclerosis. Normal growth velocity was recovered for 1 patient although her final height was below estimated target height.

Conclusions

Targeting SMO in mutated PTCH1 is an interesting strategy for long-term responses. Combination of SMOi with chemotherapy or surgery and local radiotherapy is an appealing strategy to prevent early resistance and diminish SMOi exposure, especially in young patients. Inhibition of SHH pathway causes growth and development impairment but partial recovery of the growth velocity is possible.

Prognostic Value of miR-137 in Children with Medulloblastoma and its Regulatory Effect on Tumor Progression

Medulloblastoma is a malignant tumor with high incidence and poor prognosis in adolescents and children. MicroRNA-137 (miR-137) has been found to be abnormally expressed in cancers such as pancreatic cancer. The purpose of this study is to explore the expression of miR-137 in MB and its role in cell physiological activities to determine the significance of miR-137 in the prognosis of MB. First, the expression of miR-137 in MB tissues and cell lines was analyzed by qRT-PCR. Then the Kaplan-Meier survival curve was used to analyze the significance of miR-137 expression in the prognosis, and the Cox regression model was used to explore the correlation between miR-137 expression and clinical characteristics. The effects of miR-137 on MB cell activities were analyzed by MTT assay, Transwell assays, and flow cytometry. It can be concluded from the results that the expression of miR-137 is down-regulated in MB tissues and cells. The down-regulation of miR-137 was significantly related to the poor prognosis of MB, and significantly related to clinical indicators. Up-regulated miR-137 inhibited cell proliferation, migration, invasion, and cell cycle progression, as well as induced cell apoptosis by targeting KDM1A. This study can conclude that miR-137 may be used as a prognostic biomarker of MB.

Temozolomide with irinotecan versus temozolomide, irinotecan plus bevacizumab for recurrent medulloblastoma of childhood: Report of a COG randomized Phase II screening trial

BACKGROUND

Approximately 30% of children with medulloblastoma (MB) experience recurrence, which is usually incurable. This study compared the overall survival (OS) of patients receiving temozolomide (TMZ) and irinotecan with that of patients receiving TMZ, irinotecan, and bevacizumab for recurrent MB/central nervous system (CNS) primitive neuroectodermal tumor (PNET).

METHODS

Patients with relapsed/refractory MB or CNS PNET were randomly assigned to receive TMZ (150 mg/m² /day PO on days 1-5) and irinotecan (50 mg/m² /day IV on days 1-5) with or without bevacizumab (10 mg/kg IV on days 1 and 15).

RESULTS

One hundred five patients were eligible and treated on study. Median OS was 13 months in the standard arm and 19 months with the addition of bevacizumab; median event-free survival (EFS) was 6 months in the standard arm and 9 months with the addition of bevacizumab. The hazard ratio for death from the stratified relative-risk regression model is 0.63. Overall, 23 patients completed 12 courses of planned protocol therapy, 23% (12/52) in the experimental arm with bevacizumab versus 21% (11/53) in the standard arm. Toxicity profiles were comparable in both treatment arms. The estimate of the incidence of feasibility events associated with the bevacizumab arm is three of 52 (5.8%) (95% CI 1.2-16%). Events included myelosuppression, electrolyte abnormalities, diarrhea, and elevated transaminases. One intracranial hemorrhage event was observed in each arm.

CONCLUSION

The addition of bevacizumab to TMZ/irinotecan significantly reduced the risk of death in children with recurrent MB. The combination was relatively well tolerated in this heavily pretreated cohort. The three-drug regimen demonstrated a sufficient risk reduction to warrant further investigation.

Circ-SKA3 upregulates ID3 expression by decoying miR-326 to accelerate the development of medulloblastoma

Medulloblastoma (MB), the most common malignant childhood brain tumor, is a serious threat to life. Circular RNA (circRNA) is involved in the development of various cancers, including MB. We aimed to explore the role of circRNA spindle and kinetochore associated complex subunit 3 (circ-SKA3) in MB progression. Circ-SKA3 expression was elevated in MB tissues and cells. Depleted expression of circ-SKA3 inhibited MB cell proliferation, migration and invasion and induced apoptosis and cell cycle arrest, and circ-SKA3 knockdown inhibited MB growth in vivo. Mechanism analyses revealed that circ-SKA3 directly targeted miR-326 that could bind to ID3, and circ-SKA3 decoyed miR-326 to increasing ID3 expression. Rescue experiments showed that miR-326 inhibition reversed the effects of circ-SKA3 knockdown, and ID3 overexpression recovered MB cell proliferation, migration and invasion blocked by miR-326 restoration. In conclusion, circ-SKA3 functioned as an oncogene to promote the development of MB by increasing ID3 expression via decoying miR-326, hinting that circ-SKA3 might be a therapeutic target of MB.

Etoposide-Bound Magnetic Nanoparticles Designed for Remote Targeting of Cancer Cells Disseminated Within Cerebrospinal Fluid Pathways

Magnetic nanoparticles (MNPs) have potential for enhancing drug delivery in selected cancer patients, including those which have cells that have disseminated within cerebrospinal fluid (CSF) pathways. Here, we present data related to the creation and in vitro use of new two-part MNPs consisting of magnetic gold-iron alloy cores which have streptavidin binding sites, and are coated with biotinylated etoposide. Etoposide was chosen due to its previous use in the CSF and ease of biotinylation. Etoposide magnetic nanoparticles (“Etop-MNPs”) were characterized by several different methods, and moved at a distance by surface-walking of MNP clusters, which occurs in response to a rotating permanent magnet. Human cell lines including D283 (medulloblastoma), U138 (glioblastoma), and H2122 (lung adenocarcinoma) were treated with direct application of Etop-MNPs (and control particles), and after remote particle movement. Cell viability was determined by MTT assay and trypan blue exclusion. Results indicated that the biotinylated etoposide was successfully bound to the base MNPs, with the hybrid particle attaining a maximum velocity of 0.13 ± 0.018 cm/sec. Etop-MNPs killed cancer cells in a dose-dependent fashion, with 50 ± 6.8% cell killing of D283 cells (for example) with 24 h of treatment after remote targeting. U138 and H2122 cells were found to be even more susceptible to the killing effect of Etop-MNPs than D283 cells. These findings indicate that the novel Etop-MNPs have a cytotoxic effect, and can be moved relatively rapidly at physiologic distances, using a rotating magnet. While further testing is needed, intrathecal administration of Etop-MNPs holds promise for magnetically-enhanced eradication of cancer cells distributed within CSF pathways, particularly if given early in the course of the disease.

MicroRNA-31 weakens cisplatin resistance of medulloblastoma cells via NF-κB and PI3K/AKT pathways

BACKGROUND

Medulloblastoma (MB) is a malignant intracranial tumor. Cisplatin is a broad-spectrum antitumor drug. It is important to study the cisplatin resistance of MB cells for the treatment of MB. In this article, we preliminarily studied the cisplatin resistance of microRNA (miR)-31 and the possible mechanism in DAOY and UW228 cells, laying a theoretical foundation for clinical treatment of MB.

METHODS

Following anti-miR-31 and pre-miR-31 transfections, cell viability, BrdU, CyclinD1, and apoptosis levels of DAOY and UW228 cell were detected by CCK8, BrdU, and western blot. Meanwhile, migration, invasion, and western blot assay were respectively used to detect the functions of miR-31 migration and invasion. miR-31 levels were changed by cell transfection and detected by RT-qPCR. Furthermore, the related-proteins of pathways were also detected by western blot.

RESULTS

Anti-miR-31 increased DAOY and UW228 cells viability, BrdU⁺ numbers, and expression of CyclinD1. The migration/invasion rate and expression levels of MMP-9 and vimentin after anti-miR-31 transfection were increased. Furthermore, anti-miR-31 enhanced cells' cisplatin resistance and triggered PI3K/AKT and NF-κB pathways. Pre-miR-31 played opposite roles and promoted the apoptosis.

CONCLUSION

miR-31 regulated cell growth, migration, invasion and cisplatin resistance of MB cells via PI3K/AKT and NF-κB pathways.

LC-MS/MS method for quantitation of the CK2 inhibitor silmitasertib (CX-4945) in human plasma, CSF, and brain tissue, and application to a clinical pharmacokinetic study in children with brain tumors

Silmitasertib (CX-4945) as a potent and selective inhibitor of CK2 exhibited promising in vitro and in vivo anti-cancer activity. An assay employing cation-exchange solid phase extraction (SPE) followed by LC-MS/MS analysis was successfully developed and validated for the quantitation of silmitasertib in human plasma, brain tissue, and human cerebrospinal fluid (CSF). Reverse phase chromatographic separation was achieved using Synergi™ hydro-RP column (4 μm, 75 × 2.0 mm) and gradient elution with 5 mM ammonium formate aqueous solution (pH 6.5) as mobile phase A and 0.1% formic acid in acetonitrile as mobile phase B. Multiple reaction monitoring (MRM) transition of m/z 350.2 → 223.2 and m/z 316.2 → 223.2 were chosen for detection of silmitasertib and internal standard (CX-4786) respectively. Since silmitasertib concentration in patient plasma is expected to be in a wide range due to the study design, two calibration curves with range 0.2-125 ng/ml and 32-20,000 ng/ml were established. A different curve ranging from 2 to 40 ng/g was used for measurement of silmitasertib in brain tissue, while another calibration curve ranging from 0.2 to 20 ng/ml was established for CSF. All these calibration curves corresponding to different matrices showed good linearity (R² > 0.99) over the concentration range. This assay demonstrated excellent precision below 15% and accuracies between 85% and 115% within-day and between-day for all the concentration levels in each matrix. This assay was also validated for each matrix for selectivity, sensitivity, matrix effects, recovery, and stability. We applied the validated method to the analysis of plasma silmitasertib for a clinical study.

Regulatory networks between Polycomb complexes and non-coding RNAs in the central nervous system

High-throughput sequencing has facilitated the identification of many types of non-coding RNAs (ncRNAs) involved in diverse cellular processes. NcRNAs as epigenetic mediators play key roles in neuronal development, maintenance, and dysfunction by controlling gene expression at multiple levels. NcRNAs may not only target specific DNA or RNA for gene silence but may also directly interact with chromatin-modifying proteins like Polycomb group (PcG) proteins to drive orchestrated transcriptional programs. Recent significant progress has been made in characterizing ncRNAs and PcG proteins involved in transcriptional, post-transcriptional, and epigenetic regulation. More importantly, dysregulation of ncRNAs, PcG proteins, and interplay among them is closely associated with the pathogenesis of central nervous system (CNS) disorders. In this review, we focus on the interplay between ncRNAs and PcG proteins in the CNS and highlight the functional roles of the partnership during neural development and diseases.

Comprehensive identification of a two-genesignature as a novel potential prognostic model for patients with medulloblastoma

Medulloblastoma is one of the most common malignant pediatric brain tumors and has a poor prognosis and high mortality. We investigated the prognostic significance of specific gene signatures and established a novel prognostic model for medulloblastoma patients. Ninety-seven differentially expressed genes between 69 medulloblastoma samples and 4 normal cerebellum samples were identified using the GSE68956 dataset. Univariate and multivariate Cox regression analyses revealed optimal prognosis-related genes, of which PFKP and STXBP1 exhibited significant prognostic values. A risk score model was then established to assess the prognostic value of the gene signature. Kaplan-Meier survival analysis demonstrated that patients with a high risk score had significantly poorer overall survival (OS, log-rank P = 0.003308). The concordance index (C-index) of the two-gene prognostic model for OS prediction was 0.752 (95% CI, 0.740-0.764). The area under the receiver operating characteristic curve (AUC) values for predicting 3-year and 5-year survival were 0.726 and 0.730, respectively. The risk score model was further validated in the ICGC cohort and PUMCH cohort using quantitative real-time polymerase chain reaction (qRT-PCR). Cox regression analyses were performed to assess the two-gene risk score model, metastasis stage, and chemotherapy as independent prognostic factors for medulloblastoma. The C-index of the comprehensive prognostic model composed of the two-gene signature integrated with clinicopathological features for predicting OS was 0.823 (95% CI, 0.739-0.907). The AUCs of the comprehensive prognostic model for predicting 3-year and 5-year survival were 0.774 and 0.759, respectively. Thus, the two-gene risk score model is a promising prognostic biomarker for medulloblastoma.

DNA methylation profiling is a method of choice for molecular verification of pediatric WNT-activated medulloblastomas

BACKGROUND

Wingless-activated medulloblastoma (WNT MB) represents a well-characterized molecular variant accounting for 10-15% of all MB and is associated with a favorable clinical outcome. Patients with localized WNT MBs could benefit from de-intensification of combined treatment, which would require an accurate diagnosis of these tumors. However, despite the presence of molecular features related with a WNT MB signature (nuclear ß-catenin immunoexpression, CTNNB1 mutation, and monosomy 6), a prompt and reliable diagnostic verification of these tumors is not yet feasible.

METHODS

In the current study, we analyzed 78 samples of WNT MB treated in a single institute through genome-wide DNA methylation and targeted next generation sequencing to elaborate an optimal method for WNT MB molecular verification.

RESULTS

We found that DNA methylation profiling discloses significant advantages for molecular diagnostic of WNT MB. All other "routine" methods applied, such as ß-catenin immunohistochemistry, CTNNB1 mutation analysis, and detection of monosomy 6, failed to identify all WNT MB cases. Survival analysis revealed that application of a reduced radiotherapy protocol for WNT MB treatment had no influence on patients' survival. Only one patient died due to local relapse but recurrent tumor was pathologically and molecularly diagnosed as a secondary glioblastoma.

CONCLUSIONS

DNA methylation analysis should be considered as a method of choice for further clinically relevant stratification of WNT MB and for correct diagnosis of the recurrent tumors. WNT MB patients with localized disease could benefit from treatment de-intensification.

Genetics of Common Pediatric Brain Tumors

Central nervous system tumors are the most common solid tumors in pediatrics and represent the largest cause of childhood cancer-related mortality. Improvements have occurred in the management of these patients leading to better survival, but significant morbidity persists. With the era of next generation sequencing, considerable advances have occurred in the understanding of these tumors both biologically and clinically. This information has impacted diagnosis and management. Subgroups have been identified, improving risk stratification. Novel therapeutic approaches, specifically targeting the biology of these tumors, are being investigated to improve overall survival and decrease treatment-related morbidity. The intent of this review is to discuss the genetics of common pediatric brain tumors and the clinical implications. This review will include known genetic disorders associated with central nervous system tumors, neurofibromatosis, tuberous sclerosis, Li-Fraumeni syndrome, Gorlin syndrome, and Turcot syndrome, as well as somatic mutations of glioma, medulloblastoma, and ependymoma.

[Risk factors for recurrence within 2 years in children with medulloblastoma]

OBJECTIVE

To investigate the risk factors for recurrence of medulloblastoma (MB) within 2 years and their influence on progression-free survival (PFS).

METHODS

A retrospective analysis was performed for the clinical data of 123 children with MB who were admitted from January to December, 2017. According to the presence or absence of recurrence, they were divided into recurrence group with 30 children and non-recurrence group with 93 children. The risk factors for recurrence within 2 years were analyzed, and PFS was compared between the children with different risk factors.

RESULTS

Large-cell/anaplastic type and M stage were risk factors for MB recurrence within 2 years. The risk of recurrence in the children with M+ MB was 3.525 times that in those with M0 MB, and the risk of recurrence in the children with large-cell/anaplastic MB was 3.358 times that in those with classic MB (P<0.05). The survival analysis showed that the median PFS time was 20 months in the children with M+ MB, and the 20-month PFS rate was 50% ± 11% in the children with M+ MB and 81% ± 5% in those with M0 MB (P<0.05). The 20-month PFS rate was 80% ± 5% in the children with classic MB, 65% ± 10% in those with desmoplastic/nodular MB, 86% ± 13% in those with MB with extensible nodularity, and 36% ± 20% in those with large-cell/anaplastic MB (P<0.05).

CONCLUSIONS

Recurrence is an important influencing factor for the prognosis of MB, and M+ stage and large-cell/anaplastic MB are risk factors for recurrence. Children with such risk factors tend to have a low PFS rate.